By Hemang Gadhia I will admit that WhatsApp is not exactly a household name here in the United States. Therefore, some collective head-scratching might have been in order when you read that Facebook paid $19 billion to acquire the Silicon Valley-based mobile messaging startup. In fact, Twitter was flooded with glib jokes about this deal becoming the latest piece of evidence that the bursting of this next bubble is upon us. First past the post Call me a contrarian, but I simply do not see how anyone could find fault with Facebook's rationale here. Yes, $19 billion is a lot of money. But in this case, it is money very well spent. Two years ago when Facebook announced filing its S1, there was one critique that was heard time and time again. It was that Web 2.0 posterchild Facebook did not get mobile. In fact, because Facebook was behind the curve in mobile, it paid a shocking – at the time – $1 billion to acquire mobile darling Instagram. Fast-forward to Feb. 19 and Facebook now owns three of the most ubiquitous mobile applications anywhere. The combination of Facebook + Instagram + WhatsApp puts Facebook in just about every smartphone on the planet. And to make that happen, Facebook has spent about 11 percent of its overall market cap. That 11 percent means that Facebook now owns the world's biggest social networking mobile app, photo-sharing mobile app and messaging mobile app. So where two years ago the critiques were valid, now Facebook is the unquestioned 800-pound gorilla in mobile. Or as a16z analyst Benedict Evans quipped on Twitter, "Facebook is being pretty aggressive in making sure it's the next Facebook." And beyond the strategic value, the growth numbers for WhatsApp are simply mind-boggling. Numbers game Two years ago, the company had around 70 million monthly users. A year ago, that number had grown to 200 million. Now we know that number to be more than 450 million. So now the growth is accelerating. In the past four months, WhatsApp added 100 million users. Now, it is adding more than a million users each day. So how long before WhatsApp blows past Facebook's MAU numbers? A year? Less? After all, there are already far more WhatsApp users than there are Tweeters. And let us not forget that each of WhatsApp users happily pays 99 cents per year for the app, so it is not long before that revenue is quite meaningful. CHALK THIS UP as a win for Facebook. It is sending a clear message that it does not give a rat's ass about what anyone thinks about how it uses its currency. It is just looking ahead at the big prize. Five years from now, is it really that hard to imagine that Facebook would have significant mindshare on nearly every mobile phone on the planet? All in, I would say this is a master stroke for Facebook. If you have not read the Forbes story about WhatsApp founder Jan Koum, take ten minutes to read it. His journey is incredible and inspiring. Here is a guy who came to this country twenty years ago with almost nothing. His mom struggled while working hard to make ends meet. At one point, they even had to collect food stamps. And now this guy is worth $6 billion to $7 billion and will be somewhere around No. 200 on the Forbes list of global billionaires. Unreal movie script type of stuff. Only in America. Hemang Gadhia is founder/CEO of Revmetrix, a Washington-based provider of mobile data intelligence. Reach him at hemang@revmetrix.com.